610 COLLECTIONS FROM THE WESTERN INDIAN OCEAN. 



Sarcode-spicules : — (3) Tricurvate acerate, smooth, tapering gra- 

 dually to fine points ; median curve rather sharp, forming angle 

 of about 150° ; from this point arms almost straight, until just 

 before tips, which turn up slightly; size -19--22 by *006 millim. 

 (4) Equianchorate, navicular, shaft slender, smooth, curve gradual 

 and slight; palms narrow, viz. about '08 long by "0055 millim. broad, 

 tapering to sharp points at apex, square below ; tubercle slight, 

 rather elongate, length '022 millim. 



Hah. Mozambique, between tide-marks. 



Two specimens and a fragment are in the collection. The largest 

 measures 110 millini. (4| inches) in greatest height, 85 millim. 

 (3| inches) in greatest lateral expansion ; common stem 55 millim. 

 long, 20 by 10 millim. in diameter at middle of its course, rather 

 tortuous, deeply scored on one side by a main median longitudinal 

 depression. The second specimen has its branches more cylindrical 

 than those of the larger specimen ; but it has grown abnormally, some 

 of the branches being twisted back, and anastomosis occurs near the 

 base of the specimen. The description of Spongia palmata, Lamarck 

 (Ann. Mus. Hist. Nat. xx. p. 453), var. /3, recalls this sponge. The 

 typical form of the species, which I have seen at Paris, resembles it 

 more closely than does the specimen on which this var. (3 was pro- 

 bably founded ; however, microscopic examination shows S. palmata 

 to be a Chalina. While the present species resembles Besmacidon 

 fruticosa, Mont., in texture and in the structure of the skeleton, it 

 is yet quite distinct on account of its solid branches, its acerate 

 skeleton- and its tricurvate (not bihamate) flesh-spicules. D.ard- 

 ferum, Schmidt (Algiers), appears to approach it the most nearly of 

 described species, but an acerate spicule is mentioned in addition to 

 the tricurvate. B. frondosum (Ehlers), Esper, from " East Indies," 

 resembles this sponge in general appearance, but has echinating 

 spicules, some of which are strongly spined, and no tricurvate is 

 mentioned ; hence it seems to be a Clathria. 



31. Iotrochota purpurea. 

 Halichondria purpurea, Boiverbank, P. Z. S. 1875, p. 293. 



See Part I., p. 434, of this Report. 



Fine specimens, chiefly of the usual cylindrical form, and with 

 the same coarsely roughened surface as in the Australian specimens. 

 Like those specimens, too, they show a tendency to become flattened, 

 and to vary in colour from dark purple to dark green. The spicu- 

 lation is essentially the same as in the Australian specimens. The 

 maximum height is also just the same, viz. 150 millim. (6 inches). 



Hah. Etoile Island, Amirante group, 13 fms. 



Distribution. See Part I. p. 434. 



32. Iotrochota baculifera. 



See Part I., p. 435, of this Report. 



Some small specimens, in spirit and in the dry state. In the 



